I try to build an QT project using qmake. For this I need the boost library.
LIBS += -L/usr/lib/ \
-lboost_system \
-lboost_filesystem
But after running qmake, these libraries are not added to the makefile:
LIBS = $(SUBLIBS) -L/usr/X11R6/lib64 -lQt5MultimediaWidgets
-L/build/buildd/qtmultimedia-opensource-src-5.0.1/lib -L/usr/lib/x86_64-linux-gnu
-L/usr/lib/x86_64-linux-gnu/x86_64-linux-gnu -lQt5OpenGL -lQt5Multimedia -lpulse
-lQt5Widgets -lQt5Network -lQt5Gui -lQt5Core -lGL -lpthread
As expected, the linker prints many error like
/usr/include/boost/system/error_code.hpp:214: error: undefined reference to boost::system::generic_category()
If you want to take a look to the whole .pro file, go to https://raw.github.com/francisengelmann/FabScan100/master/qtTest/qtTest.pro
I am also having a similar problem with opencv. Does anyone know how to solve this issue ?
You need to run qmake again after changing the .pro file. Just removing your build directory is not enough.
Also are you sure your qmake target is linux-g++? Does the INCLUDEPATH work?
Related
I had the problem that my Library libboost_system was not working, then I added this line in my linker, and after that it works:
LIBS += -L/usr/lib/x86_64-linux-gnu -lboost_system
So my qustion is; what does -L mean here?
and why the project won't compile without it?
thanks
I am having some big headaches linking statically libcurl in MSYS2 mingw.
I installed libcurl and all the listed dependencies from here
https://packages.msys2.org/package/mingw-w64-x86_64-curl
Since I am using CodeBlocks as IDE I need to supply a whole list of libs in form of lib#?.a, please keep in mind that I know nothing of Linux world and gcc tools and command line, otherwise I wouldn't be using an IDE!
Also I am not skilled enough to compile lib packages. I just need to write some portable code to do a https post request in cpp, so I need libcurl.
Can you tell me a complete list of all the needed libs to link against ? I tried all my best but I keep getting an infinity of unresolved symbols
UPDATE
After having checked what the package config for libcurl says, I have installed all the missing libs and used the following command line:
g++.exe -o MyProg.exe obj\Release\main.o -static-libstdc++ -static-libgcc -static -m64 -lcurl -lnghttp2 -lidn2 -lssh2 -lpsl -ladvapi32 -lcrypt32 -lssl -lcrypto -lssl -lcrypto -lgdi32 -lwldap32 -lzstd -lbrotlidec -lz -lws2_32 -s
Despite that I am still getting tons of undefined references:
d:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: d:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.2.0/../../../../x86_64-w64-mingw32/lib/../lib\libcurl.a(gsasl.o):(.text+0x14): undefined reference to `gsasl_init'
[plus many other 'gsasl...' referrences]
d:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: d:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.2.0/../../../../lib\libbrotlidec.a(decode.c.o):(.text+0x2d28): undefined reference to `BrotliTransformDictionaryWord'
[plus many other 'brotli...' references]
pkg-config will tell you the necessary flags. Install it from the package mingw-w64-x86_64-pkg-config.
Run it as pkg-config --libs --static libcurl.
Copy the output into "linker flags -> other". For me the output is -L/mingw64/lib -lcurl -lnghttp2 -lidn2 -lssh2 -lpsl -ladvapi32 -lcrypt32 -lssl -lcrypto -lssl -lcrypto -lgdi32 -lwldap32 -lzstd -lbrotlidec -lz -lws2_32. Don't forget to add the --static flag, if you're not already doing so.
I have some c++ code (Snowboy demo - demo.cc) and successfully build it on my RaspPI Zero using g++:
g++ -D_GLIBCXX_USE_CXX11_ABI=0 -fPIC -I../../ -std=c++0x -Wall -Wno-sign-compare -Wno-unused-local-typedefs -Winit-self -rdynamic -DHAVE_POSIX_MEMALIGN -Iportaudio/install/include -O3 demo.cc portaudio/install/lib/libportaudio.a ../..//lib/rpi/libsnowboy-detect.a -ldl -lm -Wl,-Bstatic -Wl,-Bdynamic -lrt -lpthread portaudio/install/lib/libportaudio.a -L/usr/lib/atlas-base -lf77blas -lcblas -llapack_atlas -latlas -lasound -o demo
To debug it I try to use QtCreator and create Qt project file:
QT -= gui
CONFIG += c++11 console
CONFIG -= app_bundle
HEADERS += demo.h
SOURCES += \
demo.cc
INCLUDEPATH += ../../
INCLUDEPATH += portaudio/install/include
LIBS += -Lportaudio/install/lib \
-lportaudio \
-L../../lib/rpi -lsnowboy-detect \
-L/usr/lib/atlas-base \
-ldl -lm -lrt -lpthread \
-lf77blas -lcblas -llapack_atlas -latlas -lasound
But with this configuration in QtCreator I receive build errors:
/home/pi/Prj/snowboy/examples/C++/demo.cc:213: error: undefined reference to `snowboy::SnowboyDetect::SnowboyDetect(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
Did I forget to specify any parameters that was used with g++ in Qt project file?
Is it possible you advise me a simple way to debug c++ code with external dependencies in Raspb Pi zero?
Snowboy for some ungodly reason requires you to use -D_GLIBCXX_USE_CXX11_ABI=0 (google it). You have this flag in your command line, which is correct in the context of Snowboy, but are missing it in your .pro file. Add it.
QMAKE_CPPFLAGS += -D_GLIBCXX_USE_CXX11_ABI=0
or something like that.
You can also try downgrading your language standard option to C++98 (not recommended but should work if your demo is not using any c++11-specific code).
I personally think that any software that is still using -D_GLIBCXX_USE_CXX11_ABI=0 in 2019 needs to be scrapped or forked, but whatever floats your boat.
This question help me run the Snowboy demo on qt-creator successfully.
I will give the question a fuller answer, to help more people: You just add the code to .pro file:
QMAKE_CXXFLAGS += -D_GLIBCXX_USE_CXX11_ABI=0
LIBS+= /home/zhurui/QtProject/Test/lib/libsnowboy-detect.a \
-ldl -lm -lrt -lpthread \
/home/zhurui/QtProject/Test/portaudio/install/lib/libportaudio.a \
-L/usr/lib/atlas-base \
-lf77blas -lcblas -llapack_atlas \
-latlas -lasound
I get a strange error while building my Qt C++ project on Ubuntu Linux using GCC 5.2.1:
/usr/bin/ld: cannot find -llibmath
I include external dynamic library to maky qmake project using command:
LIBS += -L/home/rem -llibmath
and I have library file at path /home/rem/libmath.so
As I can see from compiler output:
g++ -Wl,-rpath,/home/rem/Qt/5.5/gcc_64 -Wl,-rpath,/home/rem/Qt/5.5/gcc_64/lib -o Bazis main.o builder.o -L/home/rem -llibmath -L/home/rem/Qt/5.5/gcc_64/lib -lQt5OpenGL -L/usr/lib64 -lQt5QuickWidgets -lQt5Widgets -lQt5Quick -lQt5Gui -lQt5Sql -lQt5Test -lQt5Qml -lQt5Network -lQt5Core -lGL -lpthread
all parameters are correctly send by qmake to g++.
What is the source of my problem?
The solution is simple:
I changed my .pro file from:
LIBS += -L/home/rem -llibmath
to:
LIBS += -L/home/rem -lmath
I am trying to learn Qt, I have file test.cpp that I run via the terminal using the following command:
g++ `pkg-config --cflags --libs libsbml` test.cpp -L /usr/local/lib -lsbml -lstdc++ -lm
How can I suppl the same options to Qt?
Thank you.
You could write the qmake snippet below. In short, you would need to take a look at the following qmake variables:
LIBS
INCLUDEPATH
TEMPLATE
TARGET
HEADERS
SOURCES
CONFIG
PKGCONFIG
test.pro
TEMPLATE = app
TARGET = test
INCLUDEPATH += .
LIBS += -L /usr/local/lib -lsbml -lstdc++ -lm
unix {
CONFIG += link_pkgconfig
PKGCONFIG += libsbml
}
HEADERS += test.h
SOURCES += test.cpp
In .pro file add:
LIBS += -L /usr/local/lib -lsbml -lstdc++ -lm
look at the Makefile to figure out what variables are used. The makefile is in the build folder made by Qt.